Inductance coil structure



Dec. 16, 1947. 1-1.4, BENNER ET AL 2,432,715

INDUCTANCECO-IL STRUCTURE Original Filed Jan. 25, 1944 1 VENTORM Patented Dec. 16, 1947 INDUCTANCE COIL STRUCTURE Howard J. Benner and Allan M. Hadley, Longmeadow, Mass., assignors to The F. W. Sickles Company, Chicopee, Mass., a corporation of Massachusetts Original application January 25, 1944, Serial No. 519,634. Divided and this application May 24, 1944, Serial No. 537,128

This invention relates to improvements in radio apparatus and is directed more particularly to improvements in means associated with an inductance or the like for tuning and controlling the same and to confine and control the magnetic field thereof.

This is a division of an application filed January 25, 1944, serially numbered 519,634, now Patent No. 2,413,098. granted December 24, 1946.

The principal objects of the invention are directed to a material adapted for use as cores and closures for inductances Which by reason of its novel characteristics is easily and readily formed thereby to facilitate speed and economy in manufacture.

It is known that so-called iron cores have been employed in connection with inductance units but the process of producing them requires a mold for the material consisting of finely ground iron and a binder. The material in the mold is subjected to heat and pressure and the resulting molded'object is hard and brittle and the iron particles are not likely to be dispersed uniformly therein.

According to this invention, a material is provided which is suitable for the cores, closures or other parts for inductance coils, transformers and the like. By reason of its novel characteristics the material does not have the objectionable hardness and brittleness as that of the prior art material and not only are the ferrous particles uniformly dispersed therein but parts may be made therefrom in more or less simple molds and without heat and pressure. With objects made from the material and not having the objectionable hardness and brittleness it is possible to easily and readily remove portions thereof to change or adjust the characteristics thereof within very narrow limits for tuning and other purposes.

The novel features of the invention are adapted for broad application but will be described in connection with a transformer of the intermediate type and the parts thereof.

In the drawings:

Fig. 1 is a longitudinal sectional view through a transformer embodying the novel features of the invention;

Fig. 2 is a sectional view through a closure having an inductance therein; and

Fig. 3 is an end elevational view of the closure shown in Fig. 2 to explain certain features of the invention.

Referring now to the drawings in detail, the invention will be more fully described.

2 Claims. (Cl. 175-21) A transformer 2 is shown in Fig. 1 which includes a tubular metallic outer shell 4 with primary and secondary inductance coils 6 within closures 8 in the desired spaced relation. The closures 8 are in tubes ll] of dielectric material.

Fixed condensers l2 are provided with terminals I 4 and are disposed in opposite ends of the tube 4 with washers I6 placed on the outer sides of the condensers. The ends of the tube 4 are deformed in some manner to hold the parts in place. The necessary connections, not shown; are provided between the inductance coils and condensers.

The transformer described may be called a fixed-tuned-transformer adapted for use as an intermediate transformer in a circuit such as a radio circuit. As will appear, the transformer not only embodies novel features but illustrates in part some of the uses of the material of the invention.

The so-called iron-cores of the prior art are oftentimes used with an inductance for tuning the same and to tune or vary the value of the inductance the core is moved relative thereto.

In some cases the core is fixed relative to the inductance for fixed tuning and is attempted by locating the core of a certain size in a certain way relative to the inductance. The characteristics of the cores vary, the relative disposition of the inductance and core is easily changed and the results are not satisfactory.

According to this invention as shown in Fig. 3, an inductance 6 is supported on a central tube 20 in which is placed as a core the novel material of this invention indicated by 22.

The material for the core of the tube is essentially of a ferrous magnetic nature and is preferably provided by combining finely powdered iron and litharge or lead-monoxide with the aid of glycerine to form a substantially pasty mixture which is hardenable without the aid of heat or pressure.

The iron or its equivalent is powdered to substantially the fineness of flour and with about two parts thereof and one part of litharge the same are thoroughly mixed with suflicient glycerine to provide a more or less pasty composition that is readily manipulated.

The material is poured or in some manner inserted in the tube 20 in an amount to tune the inductance as may be desired. The composition hardens to the desired extent in a few hours but not to the extent that it becomes brittle or has other undesirable characteristics. The material adheres sufficiently to the tube to prevent relative movement thereof and with the amount in the tube for a certain result there is no likelihood of changes in its effects.

The iron particles are uniformly distributed throughout the core and there being no heat or pressure employed the characteristics thereof are constant and uniform throughout.

The amount of material in the tube may be varied to provide the desired tuning effect for the inductance, that is if desired portions of the material may be readily removed or additional material added so as to provide an inductance having the correct and desired value which is maintained since there are no forces tending to vary the value.

With the prior art iron cores the value of supposedly similar cores varies so that the ace curacy of tuning an inductance is dependent on the accuracy of the cores.

In many cases it is desirable to enclose an inductance in a closure to confine the magnetic field thereof and for other purposes but the closest approximation to the desired construction has been to provide a pair of hollow half parts molded after the manner described in connection with the prior art iron cores. There are, however, air gaps in such a construction which are objectionable.

According to this invention, it is possible to completely enclose an inductance with the novel ferrous magnetic material described and may be accomplished in some suitable manner such as by pouring the material into a mold cavity and around the inductance providing a structure such as shown in Fig. 2. That is, the magnetic material may be formed to provide a closure 8 completely enclosing an inductance such as 6.

Where the inductance is enclosed it may be desired to connect the core such as 22 thereto or in another way a tube such as 29 supporting an inductance may be connected to the closure.

It will be observed that the material of the invention is of such a character as to be readily adapted for the uses described as well as other uses and that as with the inductance of Fig. 3 it is possible to provide fixed tuning to the accuracy desired while at the same time it provides a means of completely sheathing an inductance as in Fig. 2.

The invention may be embodied in other specific forms without departing from the essential characteristics thereof. Hence, the present embodiments are therefore to be considered in all respects merely as being illustrative and not as being restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all modifications and variations as fall within the meaning and purview and range of equivalency of the appended claims are therefore intended to be embraced therein.

What it is desired to claim and secure by Letters Patent of the United States is:

1. An inductance construction comprising in combination, a central support having an axial bore, an inductance mounted on the exterior of said support, a separate one-piece enclosure made from ferrous magnetic material engaging said support and completely surrounding the exposed surfaces of said inductance, and a core in the bore of said support unconnected to said enclosure and made from said ferrous magnetic material, the position and extent of said core serving to tune said inductance.

2. An inductance construction comprising in combination, a central support having an axial bore, an inductance mounted on the exterior of said support, a separate one-piece molded enclosure made from ferrous magnetic material engaging said support and completely surrounding the exposed surfaces of said inductance, and a core in the bore of said support made from said ferrous magnetic material and unconnected to said enclosure, said magnetic material including powdered iron, litharge and glycerine, the position and extent of said core serving to tune said inductance.

HOWARD J. BENNER. ALLAN M. HADLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 844,578 Cavanagh Feb, 19, 1907 874,908 Fritts Dec. 24, 1907 1,315,365 Harnm Sept. 9, 1919 1,572,869 Adams Feb. 16, 1926 1,647,737 Legg Nov. 1, 1927 1,940,228 Polydoroif Dec. 19, 1933 FOREIGN PATENTS Number Country Date 427,322 Great Britain Apr. 15, 1935 443,552 Great Britain May 28, 1934 

